Injection nozzle



May 6, 1969 l.. D. THOMPSON ETAL INJECTION NOZZLE Filed Nov. l. 1966ATTO/@MEV United States Patent O U.S. Cl. 239-533 6 Claims ABSTRACT FTHE DISCLOSURE -An injection nozzle has a valve body housing a valvehead and a valve seat with a valve retainer such as a metal rod firmlyholding the valve head on its seat; means are provided for supplying aliquid (such as fuel) to the valve head under a pressure suiiicientlyhigh to open the valve head from its seat by elongating the retainer rodbut well within the limit of elasticity of the rod.

This invention relates generally to injection nozzles, such as thoseemployed for spraying fuel into the cylinders of an internal combustionengine, and more specifically to an outwardly-opening, orifice typenozzle wherein the valve is retained in a preloaded, closed condition bya uniform-stress spring comprising a straight wire or other similarmember under tension so that valve opening is effected by straining thewire `within its elastic limit.

'Nozzles are reviewed in chapter 9, Fuel Injection and Controls forIInternal Combustion |Engines (1962), wherein the authors, Paul G.IBurman and Frank De Luca, discuss various types of nozzles such as the(a) open, (b) closed, inwardly-opening and (c) closed, outwardlyopeningtypes, as well as various details and modifications thereof.

While these prior art nozzles undoubtedly perform their intendedfunctions, there is need for improvement. For example, most, if not all,of these prior art nozzles include a valve that is preloaded by ahelical coil spring in which the stress, across the cross-sectional areaof the spring material, is obviously not uniform at any particular valueof F, so that the well known equation, S=F/A, doesnt apply. This beingso, the volume of spring material is not utilized to its maximumeiiiciency, resulting in greater moving mass and increased stresses,such as at the valve seat and valve stop. Obviously, a helical coilspring must have a greater diameter than the wire from which it is made,which necessarily requires a larger diameter nozzle assembly and limitsengine designers as to the configuration of various adjacent enginecomponents, such as the intake and exhaust valves, etc. Furthermore,these prior art injection nozzles involve moving parts which, in orderto prevent leakage and eliminate the need for internal drain lines,requi-re precision lapped mating surfaces, adding considerably to theircost of manufacture and maintenance and friction factors to theoperation thereof.

Accordingly, a primary object of this invention is to provide a moreeflicient and less expensive injection nozzle assembly.

Another object of the invention is to provide such a nozzle assembly inwhich the nozzle valve is preloaded by a more etiicient, uniform-stressmember, thereby permitting a nozzle design of relatively small outerdiameter.

Another object of the invention is to provide such a nozzle assembly inIwhich the uniform-stress member is a wire or other similar memberstrained longitudinally within its elastic limit.

Another object of the invention is to provide an outwardly-opening,orifice type nozzle assembly, including a uniform-stress member forpreloading t-he valve.

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Still another object of the invention is to provide such a nozzleassembly that is fail-safe in that the valve cannot be injected into theengine combustion chamber in the event of spring failure. In the eventspring failure does occur, the nozzle will continue to operate as anopen type nozzle.

- Another object of the invention is to provide such a nozzle assemblywherein the structure preventing injection of the valve into thecylinder also serves as the valve stop anid a poppet type seal toprevent leakage around the open va ve.

Another object of the invention is to provide such a nozzle assemblythat is characterized by a very short stroke and low moving mass, ascompared to prior art nozzles, so as to reduce the time required for thevalve to move from its closed position to its fully open position aginstthe poppet type seal preventing leakage around the va ve.

A still further object of the invention is to provide such a nozzleassembly wherein leakage around the opening valve and into thecombustion chamber is reduced by reason of a tortuous path through whichany leakage fuel must travel.

Another object of the invention is to provide such a nozzle assemblywhich can be assembled, to a large extent, from commercially availablecomponents, so as to require a minimum of costly machining, and in whichclose lit areas are held to a minimum.

Another object of the invention is to provide such a nozzle assemblythat does not require lapped pistons thereby materially reducing themanufacturing cost.

Another object of the invention is to provide such a nozzle assemblywherein simple novel means are provided for retaining the componentsthereof in a particular relation to provide an unsymmetrical orificetype nozzle.

Another object of the invention is to provide such an assembly whereinthe nozzle holder is not subjected to pressure vessel type stresses, butmust only have adequate thread preload to prevent separation and maytherefore be made from lower strength, lighter and more easily machinedmaterials, such as aluminum.

Another object of the invention is to provide a nozzle assembly whereinvalve opening pressure and stroke are easily and independentlyadjustable, the former -without removing the nozzle from the engine.

Another object of the invention is to provide such a nozzle assemblyhaving a high spray orifice to leakage path area ratio, thus insuringthat the spray orifice is the domineering orifice or flow path andsubstantially eliminating or reducing the effect of any cylindrical orconical spray patterns that might possibly occur.

A still further object of the invention is to provide such a nozzleassembly wherein limited leakage around the valve to the poppet sealprovides squish or squeeze damping of the valve.

Another object of the invention is to provide such a nozzle assemblywherein engine cylinder pressure acts on a relatively large valve areato reduce or eliminate rebound of the closing valve and maintain thevalve tightly seated, thus preventing seat leakage; that is, the nozzleassembly is characterized by a large unbalanced area eX- posed to thecombustion chamber which reduces after injection andY results in a sharpcut-off.

Another object of the invention is to provide such a nozzle assembly4wherein flow efficiency upstream of the spray orifice is improved dueto a straight flow path, thereby increasing the overall efliciencythereof.

Still another object of the invention is to provide such a nozzleassembly wherein the injected fuel provides more etiicient cooling ofthe nozzle components, eliminating the complication of cooled nozzlesand the problems attributable t inadequate cooling.

These and other objects and advantages of the invention will becomeapparent upon reference to the following specification and theaccompanying drawings wherein:

FIGURE l is a top plan view of a nozzle assembly embodying theinvention;

FIGURE 2 is a cross-sectional view taken on the plane of line 2-2 ofFIGURE 1, and looking in the direction of the arrows;

FIGURE 3 is a cross-sectional view taken on the plane of line 3-3 ofFIGURE 2, and looking in the direction of the arrows;

FIGURES 4 and 5 are schematic illustrations of the nozzle assembly ofFIGURE 2 mounted in an engine;

FIGURE 6 is a fragmentary portion of FIGURE 2, illustrating amodifiication of the invention.

Referring now to the drawings in greater detail, FIG- URE l is asubstantially actual-size top plan view of the nozzle assembly 10, whileFIGURE 2 is an enlarged cross-sectional view. The nozzle 10 comprises aso-called nozzle holder 12 having a larger diameter vpassage 14 and anaxially aligned smaller diameter passage 16 formed therethrough, theupper portion 18 of the larger diameter passage being threaded. Theholder 12 is also Iformed with oppositely disposed ears 20 havingopenings 22 therein to receive bolts 24 by which the holder 12, and thusthe nozzle 10, is secured to the engine 26. Except for the ears andother minor details, the nozzle 10 structure is of substantiallycylindrical configuration so that the cross-sectional view of FIGURE 2is descriptive of the structure.

The holder 12 is thus adapted to receive the nozzle subassembly 28comprising an outer tube 30 fitted with or receiving therein an innertube 32, both of which may be fformed from commercially available steeltubing, the outer tube 30 having an external diameter of approximately34", for example.

Where the outer tube 30 is made from commercially available tubing, itis fitted with an external flange 34, which may be a ring brazed inplace. The internal passage 36 may be slightly enlarged by machining soas to leave the smaller diameter portion 38 at the lower end thereof,and the lower free end thereof may be formed in any suitable manner withan inwardly extending annular shoulder 40 and a short smaller diameteropening 42 for a purpose to be described.

The inner tube 32 is likewise provided with an outer flange 44 at theupper end thereof having substantially the same outer diameter as theflange 34 on the outer tube 30, the upper face of the flange 44 beingformed with an annular groove to receive the O-ring seal 46, and it isformed at the upper free end thereof with a concave spherical endsurface 48. The lower end of the inner tube 32 is machined to provide aconical or other valve seat 50 and a slot 52 formed across the free endfor a purpose to be described. Obviously, the inner and outer tubes can,alternatively, be formed by machining the same from bar stock.

One of the main features of the nozzle 10 is the steel or other suitablewire 54 extending axially, with cylindrical clearance 56, through thepassage through the inner tube 32, the wire having formed on, or securedto, the lower end thereof a valve member 58 having a conical valveportion 60 for engaging the seat 50, a collar portion 62 having adiameter providing a relatively close fit with the inner diameter of theouter tube 30 and a cylindrical free end portion 64 slidable in thesmaller diameter opening 42 at the free end of the outer tube 30. Itwill be noted that a portion of the collar 62 is flattened on oppositesides 66 and received in a slot 52 formed in the free end of the innertube 32, as shown in FIGURES 2 and 3.

The upper end of the wire 54 is provided with an enlarged threadedportion 68 flattened on opposite sides thereof, or at the end 70thereof, the threaded portion being received in an internally threadedcylindrical anchor member 72 having a flange 74 with a convex sphericalend engaging the upper concave spherical end 48 of the inner tube 32 andone or more openings 76 therein providing communication for a flow pathinto the inner tube 32.

The internally threaded passage 18 of the nozzle holder 12 has screwedtherein an externally threaded fuel line fitting 78, the inner end ofwhich bears on the flange 44 of the inner tube 32 so as to compress theO-ring 46 and provide a seal. At the same time, the fitting 78 forcesthe flange 44 down on a shim 80 positioned between the llange 44 of theinner tube and the flange 34 of the outer tube 30, the shim having aspecific purpose to be described. The fuel litting 78 is, of course,provided with a chamber 82 adapted to receive, with clearance, thethreaded upper 68 end of the wire 54 and the internally threaded anchor72. A passage 84 communicates the chamber 82 with the outer free end ofthe fitting so that a fuel line 86 may be connected to the fitting inthe usual manner, as shown in FIGUR-E 4. A lock nut 88 threaded on thefitting 78 and jammed against the nozzle holder 12 maintains the fittingsecured to the nozzle.

Another structural detail to be noted is the locating pin 90 insertedthrough aligned openings or passages in the valve holder 12, the shimand the flanges 44 and 34 on the inner and outer tubes so as to retainthese components in a definite predetermined relationship with respectto the engine 26.

Fuel flow passages 96 leading to the directional orifice 98 are formedin the lower end of the valve member downstream of the valve 60. In thecase of the unsymmetrical orifice construction shown, providing adirectional spray, the locating pin and the slot 52 in the end of theinner tube 32 receiving the flattened portion 66 of the collar 62 retainthe essential components of the assembly 10 in a definite predeterminedrelation with respect to the engine to insure that the ffuel will besprayed into the engine cylinder 100 in the proper direction, as shownby FIGURE 5', for example.

An O-ring seal 92 is provided between the inner and outer tubes near thebottom end of the nozzle, and a Teflon or other suitable seal 94 isprovided or formed on the outer diameter of the outer tube 30 as a sealbetween the engine 26 and the nozzle assembly 10.

With the above construction, it will be seen that the nozzle 10 isassembled by inserting the threaded end 68 of the wire 54 from thenotched end of the inner tube 32 until the llattened portion 66 of thecollar 6-2 is received in the slot 52. The internally threaded anchor 72may then be threaded on the threaded end 68 of the wire and tightened apredetermined number of turns, resulting in a predetermined uniformstress on the wire 54, thereby preloading the valve 60 on its seat 50.For this purpose, the anchor 72 extends above the nozzle holder 12. Thissubassembly may then be assembled into the outer tube 30 from thellanged end thereof, with the proper thickness shim 80 positionedbetween the flanges 34 and 44 to determine valve travel. The subassembly28 may then be inserted through the nozzle holder 12 from the threadedend thereof, with the pin 90 in location. The assembly 10 is completedby threading the fitting 78 into the nozzle holder 12 to the requiredtorque and tightening the jam nut 88.

Assembly on the engine is by inserting the lower end 28 of the nozzlethrough the clearance opening 102 formed in the engine and securing thesame by means of the bolts 24. The fuel line 86 is then attached bymeans -of the usual fitting.

FIGURE 6 illustrates a somewhat simpler modification wherein the stressin the spring wire 54 connected to the valve is provided not by thethreaded means shown by FIGURE 2, but by a horseshoe or other similarlyshaped washer or spacer 104 which may be inser-ted between the flat endof the tube 32 and the abutment 106 formed by the enlarged free end ofthe wire 5'4. Spacers of preselected variable thickness may be used tovary the stress in the wire, and any suitable means may be formed on thefree upper end of the wire for gripping and straining the same to permitinsertion of the spacer '4. Otherwise, the nozzle construction may bethe same as that shown by FIGURE 2.

Operation T he fuel line 86 is, of course, connected to any suitablefuel injection pump (not shown) which delivers a proper quantity of fuelto the nozzle un-der the required pressure for a predetermined durationand in timed relation to the operation of the engine cylinder 100. Thepurpose of the nozzle 10 is to spray this fuel into the cylinder, in therequired direction in the case of the nonsymmetrical nozzle shown, for aprecise period of time only and to prevent the spray or leakage of fuelat all other times.

Fuel under sutiicient pressure to unseat va'lve 60 by straining the wire54 passes through the passage 84 and the chamber '82 in the fitting 78and then through to the clearance between the wire 54 and the inner tube32. The Oring 4'6 prevents leakage of fuel between the inner end of thefitting 78 and the flange 44 of the inner tube 32. There is afluctuating force exerted lby the fuel tending to separate `the fitting78 and the nozzle holder 12, but this force is exceeded by the staticforce of the preload in the threads between fitting 78 and holder 12.Thus, the fitting 78 and holder 12 are not subjected to fluctuating highfuel pressures, which may reach 10,000 p.s.\i., but only to the higherstatic preload force between the threads.

In the modification shown by FIGURE 6, the fuel passes from the chamber82 t-o the clearance 56 between the wire and the inner tube through theopening 108 in the horseshoe-shaped spacer 104.

The fuel then travels through the efficient, straight cylindrical flowpath comprising the clearance 56 between the wire 54 and the Iinner tube32 t-o the valve 60, which is normally maintained in a closed position.by the stressed wire.

When the fuel pressure acting on the area of the valve 60 exceeds theforce of the wire plus the force due to cylinder chamber compressionpressure holding the valve closed, the valve 60 opens and fuel passes bythe valve seat 50, into the passages 96 and into the cylinder 100through the directional orifice 98.

When the pump pressure subsides, the stressed wire, which is neverstrained beyond its elastic limit, plus the pressure in cylinder chamber100 closes the valve 60 until the cycle is repeated by the pump.

It has been stated that the initial preload of the valve `60 isdetermined either by the thickness of the spacer 1014 in FIGURE 6 or thenumber of turns applied to the threaded anchor member 72 in FIGURE 2.This is easily done within acceptable limits because the nozzlestructure is such that engine combustion chamber pressure, which varieswithin wider limits, acts instantaneously on the collar `62 and theportion 6'4 in the valve closing direction.

kFor any particular nozzle design, the thickness of the shim '80determines the stroke of the valve 60. To determine the shim thicknessrequired on assembly, the wire 54 is pulled tight so that the valve 60engages the seat `50; the wire and inner tube assembly is then forceddownwardly through the outer tube 30 until the bottom of the collar 62engages the stop 40. In this condition and with shim 80 omitted from thesubassembly, the valve 60 is locked between the valve seat 50 and thestop 40 with no stroke. The .clearance between the flanges '34 and 44lis then measured and a shim having a thickness exceeding this dimensionby any desired valve stroke, .005" for example, is employed to give astroke of .005. The selected stroke must be such that the attenedportions 66 of ythe collar 62 never leave the slot 52 formed in the endof the inner tube 32.

The shoulder 40 formed on the end of the outer tube 30 not only providesa positive stop to limit the valve stroke, but, even more important, itprevents the valve 60 from being injected into the engine cylinder 100in the event that the Wire 54 should fai-l. Should spring failure occur,the valve 60 will act as a constantly open valve, at least during theinjection cycle with compression pressure acting as the valve preloadforce, and permit continued, although less eflcient, operation of thatparticular cylinder of a multi-cylinder engine.

It will be noted that the valve 60i is relatively small and that theonly frictional drag involved is the comparatively smalll surface areabetween the collar 62 and the outer -tube 30. There are no other movingparts. This being so, the nozzle 10 is characterized by an overeal'l lowmoving mass, with consequent reduced impact stresses at the valve seatand stop. Furthermore, any such impact stresses tend to be furtherreduced by the comparatively large volume of materia-l comprising thelength of the tubes, as determined by the specific engine design. It ispreferable from this -standpoint that the tubes 30 and 32 should 'be aslong as engine design will permit.

IDue to the low moving mass, the valve 60 opens and closes very quickly,providing a sharp cut-off. Cylindrical spray around the collar 62 isgreatly reduce-d or eliminated by the tortuous (two turns) that leakagefuel must travel around the collar 62, which has a close fit with theouter tube 30, and any such leakage is rapidly cut off by the poppetseal provided by engagement of the collar 62 with the stop 40. Any suchminimal leakage as may occur is not sufiicient to effect engineperformance, but does tend to provide squish dampeniug of the valve 60.

The absence in this nozzle of commonly employed internal differentialareas acted upon by fuel pressure elimin-ates internal leakage paths andthe need for leakage return lines or passages.

`Cylindrical spray patterns are also eliminated by the high orifice toleakage path area ratio, insuring that the spray orifice 98 is thedomineering orifice or llow path. This is so because, as stated above,the only leakage path is around the collar 62, this path beingrelatively small and promptly cut off by the poppet seal.

In the'nozzle shown, the outer diameter of the outer tube 30 may be onthe order of .360", and it can, of course, be even smaller, dependingupon engine fuel requirements. This feature, which is made possible `bythe use of the uniform-stress valve preloading wire, instead of theprior art helical coil spring, is a distinct advantage in that theclearance dimension 102 required in the engine head in order to installthe nozzle is on the order of .362", as illustrated in FIGURES 4 and 5,wherein the nozzle 10 embodying the invention is shown in solid linesand larger diameter prior art nozzles are shown in dotted lines 110.Obviously, the smaller nozzle space requirement gives engine designersadditional freedom in design factors such as size and location of intakeand exhaust valves 112 and 114, engine cooling cavities A116, etc.

It has been a practice in the past to provide cooling for nozzles toeliminate certain problems resulting from high nozzle temperatures. Anozzle embodying the invention, wherein the inner and outer tubes 32 and30 may comprise high fatigue strength, medium carbon alloyed steel,thin-walled tubing with clearance therebetween, has a tendency to reduceconduction of engine heat to the nozzle for a reason of the small airspace or clearance 118 between the inner and outer tubes. Furthermore,the comparatively large volume of fuel passing through the relativelysmall diameter inner tube provides significant cooling, .improving theoperation and life of the nozzle and eliminating the need for anyadditional structure to provide cooling, which would necessarilyincrease nozzle diameter.

It should be apparent that the particular cross-sectional shape of theuniform-stress member 54 is not in any way limited to a round wire, andthe more efficient uniformstress spring feature enables use ofsufficient cross-sectional area to give a safety factor in the event ofdefects such as stress risers in the spring material.

Close fit design modifications of the concentric tube design can permitthe outer tube to support any deflections of the inner tube, therebyreducing hoop stresses in the inner tube, and limited frictional dragbetween the tubes at the close fit portion 38 thereof providesadditional damping of vibrations on valve seating and the end of thevalve stroke.

It should be apparent from the above description that a nozzle embodyingthe invention fulfills the numerous objects and advantages previouslystated and that the invention has been described in sufficient detail soas to enable anyone skilled in the art to practice the same.Modifications are possible within the scope of the invention; forexample, if a symmetrical orifice design or a cylindrical spray pintledesign, as opposed to the direction orifice 98, is desired, there is noneed for the locating pin 90 and the inner tube slot 52 and fiattenedsides 66. Accordingly, no limitations are intended, except as recited inthe appended claims.

What we claim as our invention is:

1. An injection nozzle, comprising a body formed to provide a fluidinlet, a fiuid outlet, a passage connecting said inlet and said outlet,valve means controlling said outlet, said valve means comprising a valvemember normally held against a cooperating valve seat carried by saidbody, and uniform-stress means connected at one end thereof to saidvalve member normally holding said valve member in a closed position,the other end of said uniform-stress means having self centering meansanchoring the same on said body, said self-centering means minimizingeccentric loading of said uniform stress means and providing optimumsealing between said valve member and said cooperating valve seat, saiduniform-stress means comprising a straight wire-like tension member,said tension member being preloaded to a predetermined stresssufficiently below its elastic limit so that opening of said valvemember is affected by straining said tension member within its elasticlimit.

2. An injection nozzle, comprising a body formed to provide a fluidinlet, a fiuid outlet and a passage connecting said inlet and saidoutlet, valve means controlling said outlet and uniform-stress meansholding said valve means in a closed position, said uniform-stress meanscomprising a straight wire or other similar tension mem ber anchored atone end and secured to said valve means at the other end, said tensionmember being preloaded to a predetermined stress sufficiently below itselastic limit so that opening of said valve means is affected bystraining the same in tension within its elastic limit, said tensionmember extending through said connecting passage with clearancetherebetween providing a uid flow path, said connecting passage having across-sectional area greater than that of said tension member and havinga valve seat therein engaged by said valve means, said connectingpassage including stop means located on the side of said valve meansopposite said seat for limiting valve stroke and preventing said valvefrom freely separating from said nozzle in the event of failure of saidtension member, said valve means including a discharge therein, and saidvalve means and said stop are each formed with mating surfaces providingfor a positive seal against flow of fluid around said valve means whensaid valve means is in the full open position against said stop.

3. An injection nozzle according to claim 2 wherein said valve meansincludes a relatively small area close fitting surface in slidingrelationship to a containing surface of said body thereby providing ahigh discharge orifice-to-leakage path area ratio so that said dischargeorifice is the domineering path.

4. An injection nozzle, comprising a body formed to provide a fluidinlet, a fluid outlet and a passage connecting said inlet and saidoutlet, valve means controlling said outlet and uniform-stress meansholding said valve means in a closed position, said uniform-stress meanscomprising a straight wire or other similar tension member anchored atone end and secured to said valve means at the other end, said tensionmember being preloaded to a predetermined stress sufiiciently below itselastic limit so that opening of said valve means is affected bystraining the same in tension within its elastic limit, said tensionmember extending through said connecting passage with clearancetherebetween providing a fiuid flow path, said connecting passage havinga crosssectional area greater than that of said tension member andhaving a valve seat therein engaged by said valve means, and arelatively close fit interface between said valve means and a chamberwithin said body containing said valve means defining the only leakagepath around said valve means, said path including a plurality of changesin direction so as to reduce leakage therethrough.

5. An injection nozzle, comprising a body formed to provide a uid inlet,a uid outlet and a passage connecting said inlet and said outlet, valvemeans controlling said outlet and uniform-stress means holding saidvalve means in a closed position, said valve means having formed thereina nonsymmetrical discharge orifice, and means provided for maintainingsaid orifice in a predetermined positional relationship with said body.

6. An injection nozzle, comprising a body formed to provide a fluidinlet, a fluid outlet and a passage connecting said inlet and saidoutlet, valve means controlling said outlet and uniform-stress meansholding said valve means in a closed position, said uniform-stress meanscomprising a straight wire or other similar tension member anchored atone end and secured to said valve means at the other end, said tensionmember being preloaded to a predetermined stress sufficiently below itselastic limit so that opening of said valve means is affected bystraining the same in tension within its elastic limit, said bodycomprising a valve holder having a two diameter passage extendingtherethrough so as to provide a shoulder therein, the outer end of thelarger diameter portion of said passage being threaded, a subassemblyinserted into said valve holder through the end thereof having thelarger diameter threaded opening, said subassembly comprising a firstouter tubular member having an outer diameter substantially equal tothat of the s maller diameter portion of said passage through saidholder and a ange at one end thereof having a diameter substantiallyequal to the diameter of said larger diameter portion of said passagethrough said holder, said flange being seated on said shoulder, and asecond inner tubular member positioned concentrically with clearance insaid first outer tubular member, said second tubular member having aflange similar to the flange on said first tubular member, a washer typeshim disposed between said flanges, the upper surface of said flange onsaid second tubular member having a circular groove with a seal disposedtherein, said subassembly extending through the smaller diameter portionof said passage and beyond said holder, said inner tubular member havinga valve seat formed at the end thereof opposite its flanged end, saidouter tubular member extending beyond said seat and having a valve stopformed thereon, said valve means being slidable within said outertubular member between said valve seat and said stop, a fitting threadedinto said valve holder so that the end thereof compresses said seal insaid ange of said inner tubular member, said tension member extendingfrom said valve means through said inner tubular member and beyond theanged end thereof, self-centering threaded means for anchoring the endof said tension member opposite said valve means and for variablystressing the same, said fitting having a passage therethrough receivingsaid threaded means with clearance, openings in said threaded meanscommunicating said passage in said fitting with said inner tubularmember, a

9 10 seal between said inner and outer tubular members and 2,192,803 3/1940 Purdy et a1. 239-453 an exterior seal on said outer tubular member.2,901,181 8/ 1959 Bek 239-533 X References Cited ALLEN N. KNOWLES,Primary Examiner. UNITED STATES PATENTS 5 M. Y. MAR, Assistant Examiner.1,609,578 12/1926 Scott 239-453 1,740,316 12/1929 Ricardo. U'S- CL X-R-1,755,192 4/1930 Scott 239--453 X 123-32

